01-01-2013, 11:58 AM
Steer-by-Wire: Modification of Vehicle Handling Characteristics
Introduction
A control strategy of the active front wheel steering system to protect from spin and to realize the improved cornering performance
“Bifurcation in Vehicle Dynamics and Robust Front Wheel Steering Control” by Eiichi Ono, Shigeyuki Hosoe, Hoang D. Tuan, and Shun’ichi Doi.
Acceptable steering feel after the elimination of the link between steering wheel and road wheels.
“A Control System Methodology for Steer-by-Wire Systems” by Sanket Amberkar, Farhad Bolourchi, Jon Demerly and Scott Millsap.
Experimental Determination of Transfer Functions
“Modern Control Engineering” by Katsuhiko Ogata.
What is Steer-by-Wire?
Unlike the conventional steering system where a hand-operated steering wheel is used to turn the front wheels through the steering column, steer-by-wire technology removes the mechanical and physical links between the driver (steering wheel) and the front wheels, and replace them with electronic actuators and other components.
The Objectives
Simulate a conventional steering system
Design and replace with active steering by-wire system
New system must be comparable in response from a driver’s perspective
working principle
driver supply torque .
supplied torque measured by the device .
processer working starts .
motor supplies neccesary input .
resulting torque is measured.
torque is applied to the tie rod .
Many Advantages
No steering column – Simplify the design of a car’s interior, giving the driver more space as well as better safety in case of a crash (no intrusion of the steering column).
The absence of steering shaft and gear reduction mechanism allows much better utilization of the engine’s compartment.
Decreases the total weight of the car issuing better energy reduction effectiveness.
Easier implementation of left or right-hand driving.
No noise or vibration can reach the driver’s hands.
The most significant benefit is the ability to electronically augment the driver’s steering input depending of drive’s conditions, also called active steering.
Conclusion
Steer-By-Wire already exists in military jets and commercial airplanes.
BMW introduced Steer-by-Wire in its 2000 prototype BMW Z22 but due to the cost involved, only implements certain components of steer-by-wire technology; they call it Active Steering.